It is known that prostaglandin E.sub.1 (PGE.sub.1) exists in a trace amount in a living body, has a broad range of physiological actions and the like, but lacks chemical stability. Therefore, an improvement in the formulation of a preparation and modification of PGE.sub.1 have been considered. In particular, a PGE.sub.1 precursor (prodrug) has been drawing attention. It is therefore an object of the present invention to provide a new use of a PGE.sub.1 precursor.